Keisuke Yamashita was a Japanese voice actor and actor born in Tokyo on September 25, 1941. He passed away on June 8, 2024, at the age of 83. His career in the entertainment industry was extensive, spanning several decades from the 1970s through the 2010s. Yamashita was a graduate of the Tokyo Metropolitan Art High School and began his career in his youth with the theater troupe Himawari. In 1967, he joined the theatre company Theater Echo, where he remained a member and actively performed in its productions from 1969 until 2015.

Yamashita possessed a distinctive masculine voice, characterized as intense, sharp, and high-pitched. This unique vocal quality led to him being frequently cast in antagonist roles across both anime and tokusatsu (live-action special effects) productions. He became particularly well-known for his extensive work in the Kamen Rider series, providing voices for numerous monsters, which established him as a prominent figure in the genre. A significant and enduring contribution to popular culture is his creation of the iconic "It!" shout used by the Shocker combatants in the original Kamen Rider series, which began as an ad-lib during post-recording and was subsequently adopted for the show.

His anime voice acting portfolio is vast and includes roles in many classic and long-running series. Among his most recognized roles are Goro in UFO Senshi Daiapolon and its sequel UFO Senshi Daiapolon II, Dan Araiso in Reideen the Brave, and Nemo the Martial Artist in Mobile Suit SD Gundam: SD Gundam Legend. He also voiced Gaulois in Tico and Friends, Isshuu Mokusuke in Tentō Mushi no Uta, Ralmophan in Dirty Pair Flash, and Hiss in the Star Blazers franchise (known as Uchū Senkan Yamato in Japan). His other anime credits span a wide range of popular titles, including The Slayers, Rurouni Kenshin, Master Keaton, Lupin the Third Part II, Galaxy Express 999, Berserk, and Akuma-kun.

Beyond anime, Yamashita had a substantial career in tokusatsu, providing voice work for numerous characters in the Super Sentai and Kamen Rider franchises. His credits include roles in series such as Chōdenji Bioman, Kamen Rider Super-1, and Kamen Rider (Skyrider). He also appeared in live-action films, including Godzilla: Final Wars in 2004 and the television series Kamen Rider Hibiki in 2005. His work extended to video games as well, lending his voice to titles like Super Robot Wars Z. Over his long career, Yamashita collaborated frequently with many other voice actors, including盐屋浩三 (Kōzō Shioya), 西村知道 (Tomomichi Nishimura), and 饭塚昭三 (Shōzō Iizuka).